Delaware County has been ordered to reassess all of its residential and commercial properties, effective Jan. 1, 2021, after a trial judge found the county violated the state constitution as a result of going nearly two decades without a reassessment.

Two Delaware County families whose new homes were assessed at what they said were exceedingly high percentages of their fair market values argued that the county has been improperly using 1998 as its base year for assessments, leading to “a system of property taxation that is profoundly inequitable in direct violation of the uniformity clause of the Pennsylvania Constitution,” according to court papers.

“The county's continued use of a 1998 base year rests upon a fiction that is demonstrably untrue, namely, that property values do not change over an extended period of time,” plaintiffs James and Lenore Kaufman and Peter and Ellen Bodenheimer argued in a November 2016 filing.